Table 2.

Summary of findings from studies that measured blood leucine concentration profiles and post-prandial rates of muscle protein synthesis at rest in younger adults.

References	Participants	Study Design/Intervention	Muscle fraction for MPS measurement	Evidence supporting “leucine trigger” hypothesis	Blood leucine concentration profile	Post-prandial rates of MPS profile
Pinckaers et al. (32)	Healthy, recreationally active males (23 ± 3 yr)	Double-blind, Parallel RCT 30 g milk protein (n = 12) 30 g wheat + milk protein (n = 12) 30 g wheat (n = 12)	Myofibrillar 0–5h	No	Peak plasma leucine concentrations: Milk (353 ± 45 μM) > wheat + milk (301 ± 44 μM) > wheat (280 ± 37 μM). Overall plasma leucine concentrations (AUC): Milk (36 ± 7 mmol·300 min/L) > wheat + milk (25 ± 9 mmol·300 min/L) > wheat (22 ± 3 mmol·300 min/L).	Wheat + milk (0.067 ± 0.032 %/h) > milk (0.059 ± 0.024 %/h) > wheat (0.053 ± 0.025 %/h) at 0–2 h. Wheat (0.058 ± 0.013 %/h) > Wheat + milk (0.054 ± 0.036 %/h) > milk (0.049 ± 0.017 %/h) at 2–5 h. Wheat + milk (0.059 ± 0.025 %/h) > wheat (0.056 ± 0.012 %/h) > milk (0.053 ± 0.013 %/h) at 0–5 h.
Luiking et al. (33)	Healthy, untrained males and females (23 ± 1 yr)	Single-blinded, RCT 0.21 g/kg/bw casein (n = 12) 0.21g/kg/bw soy (n = 10)	Mixed 0–4h	Yes	Overall plasma leucine concentrations: Soy (128 ± 13 μM) > casein (95 ± 7 μM) at 0 h. Soy (117 ± 9 μM) < casein (121 ± 5 μM) at 4 h.	Soy > casein.

AUC, area under curve; MPS, muscle protein synthesis; RCT, randomized controlled trial.

Values are presented as means ± SE.